org.apache.jxtadoop.security.UserGroupInformation.java Source code

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Here is the source code for org.apache.jxtadoop.security.UserGroupInformation.java

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/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.jxtadoop.security;

import java.io.IOException;
import java.security.AccessController;
import java.security.Principal;
import java.util.Set;

import javax.security.auth.Subject;
import javax.security.auth.login.LoginException;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.jxtadoop.conf.Configuration;
import org.apache.jxtadoop.io.Writable;

/** A {@link Writable} abstract class for storing user and groups information.
 */
public abstract class UserGroupInformation implements Writable, Principal {
    public static final Log LOG = LogFactory.getLog(UserGroupInformation.class);
    private static UserGroupInformation LOGIN_UGI = null;

    private static final ThreadLocal<Subject> currentUser = new ThreadLocal<Subject>();

    /** @return the {@link UserGroupInformation} for the current thread */
    public static UserGroupInformation getCurrentUGI() {
        Subject user = getCurrentUser();

        if (user == null) {
            user = currentUser.get();
            if (user == null) {
                return null;
            }
        }

        Set<UserGroupInformation> ugiPrincipals = user.getPrincipals(UserGroupInformation.class);

        UserGroupInformation ugi = null;
        if (ugiPrincipals != null && ugiPrincipals.size() == 1) {
            ugi = ugiPrincipals.iterator().next();
            if (ugi == null) {
                throw new RuntimeException("Cannot find _current user_ UGI in the Subject!");
            }
        } else {
            throw new RuntimeException("Cannot resolve current user from subject, " + "which had "
                    + ugiPrincipals.size() + " UGI principals!");
        }
        return ugi;
    }

    /** 
     * Set the {@link UserGroupInformation} for the current thread
     * @deprecated Use {@link #setCurrentUser(UserGroupInformation)} 
     */
    @Deprecated
    public static void setCurrentUGI(UserGroupInformation ugi) {
        setCurrentUser(ugi);
    }

    /**
     * Return the current user <code>Subject</code>.
     * @return the current user <code>Subject</code>
     */
    static Subject getCurrentUser() {
        return Subject.getSubject(AccessController.getContext());
    }

    /**
     * Set the {@link UserGroupInformation} for the current thread
     * WARNING - This method should be used only in test cases and other exceptional
     * cases!
     * @param ugi {@link UserGroupInformation} for the current thread
     */
    public static void setCurrentUser(UserGroupInformation ugi) {
        Subject user = SecurityUtil.getSubject(ugi);
        currentUser.set(user);
    }

    /** Get username
     * 
     * @return the user's name
     */
    public abstract String getUserName();

    /** Get the name of the groups that the user belong to
     * 
     * @return an array of group names
     */
    public abstract String[] getGroupNames();

    /** Login and return a UserGroupInformation object. */
    public static UserGroupInformation login(Configuration conf) throws LoginException {
        if (LOGIN_UGI == null) {
            LOGIN_UGI = UnixUserGroupInformation.login(conf);
        }
        return LOGIN_UGI;
    }

    /** Read a {@link UserGroupInformation} from conf */
    public static UserGroupInformation readFrom(Configuration conf) throws IOException {
        try {
            return UnixUserGroupInformation.readFromConf(conf, UnixUserGroupInformation.UGI_PROPERTY_NAME);
        } catch (LoginException e) {
            throw (IOException) new IOException().initCause(e);
        }
    }
}